In certain embodiments of traditional organic light emitting diodes (OLEDs), two electrodes are separated by an electroluminescent layer. Because photons are generated within the electroluminescent layer by the recombination of electrons and electron holes, one of the electrodes is typically made from a transparent material to allow the emitted photons to escape the device. For example, a common transparent electrode material is indium tin oxide (ITO). The transparent conductive ITO electrodes widely used in OLED devices are typically 85-90% transparent and have approximately 10 ohm per square (Ω/□) sheet resistance. One major drawback of ITO electrodes consists of their high optical losses due to their high refractive index: optical losses are enhanced by the light reflections associated with the high refractive index of ITO relative to the transparent carrier substrate (generally glass in current OLED devices). This high optical loss has significantly reduced the external quantum efficiency (EQE) of OLED devices. A further drawback of using ITO is that the material is relatively expensive.
There remains a need in the art to overcome the abovementioned drawbacks, as well as generally to develop new methods and materials for manufacturing efficient and low cost organic electrical devices (OEDs) such as electroluminescent devices (ELDs). Ideal methods would utilize materials that are readily available or easily prepared, provide significant enhancements in device output (efficiency and/or total output), minimize the number of process steps, and/or provide highly reproducible results.